全文获取类型
收费全文 | 768篇 |
免费 | 78篇 |
国内免费 | 3篇 |
专业分类
化学 | 618篇 |
晶体学 | 4篇 |
力学 | 2篇 |
数学 | 16篇 |
物理学 | 209篇 |
出版年
2023年 | 7篇 |
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 22篇 |
2019年 | 22篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 33篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 47篇 |
2012年 | 40篇 |
2011年 | 53篇 |
2010年 | 39篇 |
2009年 | 25篇 |
2008年 | 53篇 |
2007年 | 40篇 |
2006年 | 28篇 |
2005年 | 39篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 13篇 |
1998年 | 3篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 19篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1968年 | 5篇 |
1967年 | 3篇 |
排序方式: 共有849条查询结果,搜索用时 15 毫秒
61.
62.
63.
S. Nagadome H. Oda Y. Hirata H. Igimi A. Yamauchi Y. Sasaki G. Sugihara 《Colloid and polymer science》1995,273(7):701-707
In order to study how the bile salts and lipids behave in the vicinity of microvillus, the transport properties of a sodium salt of deoxycholic acid (NaDC) and its mixture with monooleoylglycerol (MO) through artificial membranes were investigated in 0.15 M NaCl saline solution at 37°C.The hydrodynamic radius of MO-solubilized micelles was estimated to be approximately 17–20 Å from the transport study. The thermodynamically stable MO-NaDC mixed micelles formed above critical micelle concentration in the higher region of mole fraction of NaDC in the mixture (X
NaDC>ca. 0.6), can behave as a single species in transport process and freely pass through the porous membranes of both pore sizes, 0.01 m and 0.1 m.The permeabilities of MO-NaDC mixed micelles are large compared with those of pure NaDC micelles. MO molecules solubilized may probably enhance the interaction between MO and NaDC molecules by better contacting with the respective hydrophobic groups in a mixed micelle (the flexible structure of MO molecule enables it), and in this situation, the smaller micelles compared with those of pure NaDC must be more favorable. 相似文献
64.
65.
66.
High‐Loading Nano‐SnO2 Encapsulated in situ in Three‐Dimensional Rigid Porous Carbon for Superior Lithium‐Ion Batteries
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hairong Xue Dr. Jianqing Zhao Jing Tang Hao Gong Prof. Ping He Prof. Haoshen Zhou Prof. Yusuke Yamauchi Prof. Jianping He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4915-4923
Tin oxide nanoparticles (SnO2 NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m2 g?1), and the SnO2 NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO2@OMC composite material can deliver an initial charge capacity of 943 mAh g?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g?1, even exhibit a capacity of 503 mA h g?1 after 100 cycles at 160 mA g?1. In situ encapsulation of the SnO2 NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO2 particles (SnO2/OMC). The significantly improved electrochemical performance of the SnO2@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO2 NPs. 相似文献
67.
We report the discovery of a new superconducting phase in highly correlated 3d electron systems. The compound is beta-vanadium bronze, beta- Na0.33V 2O5, in which the charge-ordered phase collapses under hydrostatic high pressure and a pressure-induced superconducting phase appears around T(S C)=8 K, P=8 GPa. This report presents the first observation not only of superconductivity in vanadium oxides but also of a phase transition from charge ordered to superconducting on a pressure-temperature (P- T) plane. The phase diagrams seem to have universal aspects across the classes of materials. This indicates a profound physics of superconductivity in highly correlated electron systems. 相似文献
68.
Junji Yamauchi Takashi Ando Yasuhiro Akimoto Hisamatsu Nakano 《Fiber and Integrated Optics》1996,15(4):353-363
A wavelength filter consisting of single-mode and few-mode fibers is investigated numerically. A simple finite-difference beam-propagation method, in which a transparent boundary condition can be imposed, is developed for circularly symmetric waveguides. After confirming the validity of the numerical method by the mode-mismatch loss, we calculate the propagating field in the fiber wavelength filter, in which interference between LP01, and LP02 modes occurs. To improve the filtering operation, a depressed-index fiber is employed for the few-mode fiber. The effects of the radius and refractive index of the depressed section on the transmission power are revealed and discussed. Power is suppressed to less than 0.1% at 1.3 μm, while maintaining power transmission of more than 85% at 1.55 μm. It is also found that the filtering operation shifts to higher wavelengths as the input power is increased when we choose a self-focusing nonlinear material in the depressed section. 相似文献
69.
70.
The behavior of arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, dimethyl-R-arsine oxides, and trimethyl-R-arsonium compounds (R = carboxymethyl, 2-carboxyethyl, 2-hydroxyethyl) toward sodium borohydride and hot aqueous sodium hydroxide was investigated. The arsines obtained by sodium borohydride reduction of the undigested and digested solutions were collected in a liquid-nitrogen cooled trap, separated with a gas chromatograph, and detected with a mass spectrometer in the selected-ion-monitoring mode. The investigated arsenic compounds were stable in hot 2 mol dm?3 sodium hydroxide except arsenobetaine [trimethyl(carboxymethyl)arsonium zwitterion] that was converted to trimethylarsine oxide, and dimethyl(ribosyl)arsine oxides that were decomposed to dimethylarsinic acid. Hydride generation before and after digestion of extracts from marine organisms allowed inorganic arsenic, methylated arsenic, arsenobetaine, and ribosyl arsenic compounds to be identified and quantified. This method was applied to extracts from shellfish, fish, crustaceans, and seaweeds. 相似文献